Hello Emacs developers,

The inlined patch implements the (already expected) generation of
multi-file package long description from a potential README file
residing inside the package’s content directory.  Currently Emacs only
implements the long description generation from commentary sections and
for single-file packages.

This behavior is documented in ‘(elisp) Multi-file Packages’ and the
function ‘package-upload-buffer-internal’ from ‘package-x.el’ had a
‘FIXME: Get it from the README file.’ right on the spot of this
implementation.


Let me know if any change is necessary.  Thanks!